Rivet blank holder transversely movable between header and ejector stations



June 5, 1956 H WEIGAND RIVET BLANK HOLDER TRANSVERSELY MOVABLE BETWEEN HEADER AND EJECTOR STATIONS Filed May 26, 1955 N 2 m N V 7-4? 8 z\ I i i w W A A A I w x M m Q &

m 83 I g} k INVENTOP Heinz Wez' qcznd ATTORNEYS -tions on a double press.

United States Patent RTVET BLANK HOLDER TRANSVERSELY MOV- ABLE BETWEEN HEADER AND EJECTOR STATIONS Heinz Weigand, Frondenberg (Ruhr), Germany, assignor of one-half to Peltzer & Ehlers K. G., Krefeld, Germany Application May 26, 1953, Serial No. 357,500

Claims. (Cl. -11) This invention relates to the manufacture of rivets, and more particularly to a method and apparatus for the manufacture of cold-pressed hollow and semi-hollow rivets.

Wire being much lower in price than tubular material which hitherto has been practically employed in the manufacture of rivets, while semi-hollow rivets had to be drilled, the method described herewith enables semihollow and hollow rivets to be manufactured at far lower costs.

As is known, such rivets have already been manufactured according to the progressive pressing method. Immaterial, however, whether it was a question of springoperated dies or stationary dies, always a sleeve had to be employed for ejecting the finished rivet, which sleeve had be placed over the punching tool.

These disadvantages are well-known and have hitherto been considered as being insurmountable.

In addition to this disadvantage, neither thin-walled hollow nor semi-hollow rivets can be produced, because the ejector sleeve cannot stand more weakening of its wall; the same holds true for rivets having lengthened shanks, which rivets hitherto had to be drilled.

Furthermore, it was disadvantageous that metal rivets having a shearing strength of more than 23 kg. per sq. mm. could not be manufactured at all according to the above method of prior art.

One of the principal objects of the present invention is to provide an efficient method for manufacturing hollow and semi-hollow rivets, and apparatus for carrying out that method.

In accordance with a further feature and object of the present invention the apparatus includes a sleeveless, i. e., a strong punch and an additional solid ejector. By eliminating the sleeve the punch is strengthened to such a degree as to make it impossible for same to break, and the use of the solid ejector guarantees the ejection of the finished rivet.

Another advantage results from the use of an adjustable lower die which in one operation is brought in contact with a spring-actuated punch housing into which enters the punch which by the simultaneous and continuous pressure of an upper and a lower die, respectively, finishes the rivet. After separation of the dies by the return of the upper die housing the lower die, being mounted in a vertical slide, rolls down a cam structure toward the ejecting position, Where the rivet is ejected. These means are especially employed in the manufacture of semi-hollow rivets; when manufacturing hollow rivets, however, it is suitable to employ two punching opera- In manufacturing hollow rivets on such a double press, which is provided With two upper dies, the lower die, however, also executes only the same operation as with the single punch press; i. e., the lower die is brought into contact with the spring-actuated punch housing and, by the action of the punch in co-action with the upper die, the spring being under tension, first proice Patented June 5, 1956 duces a semi-hollow rivet, then at the second operation of the upper die housing the lower die comes into contact with a stationary ejector housing, where the rivet is finished and calibratedby the second upper die and ejected on the return of said upper die.

The various objects and advantages of this invention will be more apparent upon considering the following detailed description of a typical embodiment thereof illustrated in the accompanying drawing which shows a longitudinal section of an apparatus for manufacturing said rivets.

The drawing illustrates in a simplified way the essential parts of an apparatus for manufacturing semi-hollow rivets. A punch 1 is removably inserted into a movable frame 17 and rigidly attached thereto by means of a set-screw 3. In the usual manner, the frame 17 is movable in the direction of the longitudinal axis 21 of punch 1 as indicated by an arrow A. A body member 9 being provided with a die 5 and positioned opposite to the punch 1 is adapted to be moved rectangular to the axis 21, the movement of member 9 being terminated in one direction by a cam structure 2 rigidly attached to the frame 17. In the opposite direction, the movement of the body member 9 is terminated by a stop 8 and a spring 10, each of them being preferably adjustable.

A pulley 12 rotatably arranged on the body member 9 is adapted to roll upon a curved surface 2' of the cam structure 2, the latter abutting a buffer 22 actuated by a spring 11. With a smooth side 9a remote from the punch 1, the body member 9 is slidable upon a smooth side 23 of a stationary frame 18, to which the stopping means 8, 10 and buffer means 22, 11 are attached.

The frame 18 has two bores 24 and 25 respectively running parallel with the axis 21. The bore 24 surrounds a pressing member counteracting to the first pressing member constituted by the punch 1 and its frame 17, this pressing member being fully explained hereinafter. In the other bore 25 of the frame 18, there is slidably mounted an ejector 6 removably attached to a shaft 14 driven by a main eccentric (not shown). The same eccentric is adapted to drive a shaft 15 of the second pressing member in the direction of an arrow B, i. e., in a direction opposite to the direction of arrow A.

Besides the shaft 15, the second pressing member comprises a plate 29 attached to the shaft 15 and carrying a holder 13, a piercing tool such as a core bar 7 removably attached to the holder 13, a tube-like member 28 and a strong spring 16 interposed between the plate 29 and the member 28, the latter having an integral guiding portion 20. The holder 13 and the core bar 7 are slidably arranged within a central bore 27 of the tube-like member 28, whereas the latter and the plate are slidable within the bore 24 of the stationary frame 18. A shoulder 26 of this frame is adapted to hold the tube-like member 28 against the action of the spring 16 in a position as shown in the drawing, whereas the outer endof this member lies flush with the smooth side 23 of the frame 18.

The die 5 slidably positioned within a bore 30 of the bodymember 9 has a central bore 19 and a flange portion 31, the latter abutting at one side with the side 23 of the frame 18 and at the other side with a shoulder 32 of the body member 9. At a side 9b of this member adjacent to the punch 1, the bore 19 is enlarged to an end portion 33.

For pressing a blank 4 into a semi-hollow rivet, the blank has to be cut off from a wire coil and inserted into the die 5 by usual devices (not shown). At the beginning of a fore stroke of the movable first pressing 3 tion as illustrated in the drawing. At this position, the die 5, that is, its central bore 19 and the inserted blank 4, lies in line with the central axis 21 of the punch 1 and s with the core bar 7.

Under the pressure of punch 1 striking in the direction of arrow A, the die 5 is pushed to the left and itself pushes the tube-like member 28 in the same direction against the action of the spring 16. Simultaneously, the shaft 15, driven by the main eccentric in the direction of arrow B, pushes the core bar 7 to the right over the holder 13 and the plate 29, the latter compressing the spring 16 from the other side as the member 28, whereby this spring is strongly compressed. The piercing head 7a of the core bar 7 entering into the blank 4 forms a hollow rivet shaft within the narrow portion of the bore 19 and displaces some blank material into the enlarged end portion 33, wherein the solid rivet head is shaped by the counter action of the piercing head 7a and of the punch 1. By this means, a semi-hollow rivet is formed of a blank at a single pressing action of the apparatus according to the invention.

This new and useful method of manufacturing semihollow rivets from blanks at a single stroke of counteracting pressing members may be carried out even if the blank material has a rather high mechanical power of resistance. Only a single punch and a single counteracting piercing tool are necessary, each of them merely having to be movable in a linear direction, and it is possible to exert upon the pressing members a substantially higher pressure than with other known apparatus.

At the rear stroke of the pressing members, the die 5, the tube-like member 28 and the holding means 13, 29 of the core bar 7 are released from any outer pressures exerted upon them from opposite directions as explained above. Now, the highly compressed spring 16 presses the tube-like member 28 to the right until its guiding portion 20 abuts with the shoulder 26, whereby the die 5 is simultaneously removed into its position as shown in the drawing. Furthermore, the spring 16 pushes the plate 29 to the left, thereby pulling the piercing head '70 with great power out of the rivet shaft.

In continuance of th erear stroke of the first pressing member, supported by the action of the buffer spring 11, the curved surface 2 of the cam structure 2 releases the body member 9. Then, the tensioned spring 10 pushes this member in a direction transversely of the direction of the axis 21 until the bore 19 of the die lies in line with the ejector 6, that is, with the central axis of the bore 25 spaced in the moving direction of the body member 9 from the bore 24 of the stationary frame 18. Now the shaft 14 and the ejector 6 are driven by the main eccentric in the direction of arrow B, the ejector 6 thereby expelling the pressed rivet from the die 5. Then, a new blank 4 may be inserted into the die 5 and a further fore stroke of the pressing members begins.

The use of a special ejector for removing a finished rivet from the die 5 is much better than the use of the piercing tool 7 for the same action. In the latter case, a special stroke of this tool would be necessary, substantially reducing the output of the apparatus. Furthermore, on that additional stroke the spring 16 would have to be uselessly compressed, requiring additional power from the main eccentric, which has to be rotated in any case for the next pressing stroke of the tool 7. The momentum exerted upon the eccentric sufficient to cause such a stroke is a steady one during a whole rotation and may be efiiciently used for the action of the ejector.

Contrary to the known apparatus for cold-pressing rivets from blanks, inventors apparatus does not require any complicated steering devices for the control of rotating punchand die-frames as does the known apparatus. As known by all skilled in the art, such corn- -plicated devices cause many troubles and .they have to be continuously surveyed and often repaired, thereby reducing the output of the machine.

In manufacturing hollow rivets the operation is the same, except that it takes place on a double press, not shown. This press operates with two pressure actions of the upper die housing and is provided with a second upper die which calibrates the pre-shaped hollow rivet in its lowest position, the lower die remaining stationary.

While the method herein described, and the form of apparatus for carrying this method into elfect, constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to this precise method and form of apparatus, and that changes may be made in either without departing from the scope of the invention which is defined in the appended claims.

I claim:

1. An apparatus for cold-pressing blanks into rivets, comprising two counteracting and only linearly movable pressing members, one of these members containing a punch and the other one containing a piercing tool such as a core bar, a die movably arranged between the said pressing members and being movable in a direction perpendicular to the moving directions of the said pressing members respectively, a rivet ejector movable parallel to and spaced from the said piercing tool in the moving direction of the said die and a cam structure attached to the first named pressing member and adapted to control the movement of the die in cooperation with a stop and a spring in such a manner that the said die charged with a blank is moved in line with the said punch and the said piercing tool respectively, held in this position during a pressing stroke of the said pressing member, is then moved in line with the said ejector and held in this other position during action of the said ejector, whereby a semi-hollow rivet pressed of the said blank is removed from the said die.

2. In an apparatus as claimed in claim 1, a body member having the die positioned therein and being slidable along a smooth side of a stationary frame containing a bore for the said other pressing member and a bore for the ejector, the said bores being spaced from each other in the direction of movement of the said body member.

3. An apparatus as claimed in claim 2, the said other pressing member slidable within said bore of the stationary frame comprising a mechanically driven shaft, 21 plate attached to the said shaft, a tube-like member, a spring interposed between the said plate and the said tubelike member, a holder attached to said plate and a piercing tool attached to said holder, the latter and the said piercing tool being slidable within a central bore of the said tube-like member.

4. An apparatus as claimed in claim 2, the die being slidably positioned within the body member in such a manner as to lie flush with a side of the said body member remote from the punch when not pressed by the said punch and to somewhat protrude from this position into the bore of the stationary frame containing the other pressing member when pushed by the said punch into the said bore, thereby itself pushing the tube-like member of the said other pressing member rearwardly against the action of the spring interposed between the said tubelike member and the plate attached to the driven shaft of the said other pressing member.

5. An apparatus for cold-pressing blanks into rivets, comprising two counteracting and only linearly movable pressing members, one of the said members containing a movable frame and a punch attached to the said frame and the other of the said pressing members being slidable in a bore of a stationary frame and comprising a mechanically driven shaft, a plate attached to the said shaft, a tube-like member, a spring interposed between the said plate and the said tube-like member, a holder attached to the said plate and a piercing tool attached to the said holder, the latterand the said tool being slidable within a central bore of the said tube-like member, the said apparatus comprising a movable body member, a die slidably positioned in the said body member, a rivet ejector slidable Within another bore of the said stationary frame spaced in the moving direction of the said body member from the said first named bore of the said stationary frame and a cam structure attached to the said movable frame, the said body member being slidable along a smooth side of the said stationary frame in a path perpendicularly to the moving directions of the said pressing members respectively in such a manner as to bring a central bore of the said die adapted to receive a blank in line with the said punch and the said piercing tool respectively and spring means to bring the said die in line with the said ejector, the movements of the said body member being controlled by the spring means and said cam structure in cooperation with a stop means attached to the said stationary frame.

References Cited in the file of this patent UNITED STATES PATENTS 

